In the present study the association between angiographically demonstrated coronary artery disease lipid subfractions and insulin in Caucasians, Asian migrants to the UK and Asians in India was studied. Patients having at least one angiographic lesion of more than 50% were recruited and angiograms scored by two independent observers, blindly. There were 87 Caucasian, 83 British Asian and 30 Indian Asian patients. Lipid subfractions measured were cholesterol, HDL cholesterol, triglyceride, apo A1, apo B, Lp(a). Estimation of glucose and insulin was carried out at fasting and after two hours of oral 75 g glucose. Asians were younger than Caucasians. They did not differ in their body mass index, systolic and diastolic blood pressure or cigarette consumption. In all three ethnic groups cholesterol, LDL cholesterol and apo B showed significant positive association. Insulin levels at fasting or post glucose challenge failed to show any association. Apo B may be an additional marker for coronary artery disease in the ethnic groups studied.